This should definitely used the official NDK, complexity of this port probably comes from:

porting dependencies (including, but not limited to, Guile)

rewriting the autotools / Makefile wizardry for the very special Android case

writing a gfx backend which can run on Android (it could be a simple one as mod-soft or a fancy one as mod-gles2 but anyway, mod-gl1 won't work because it relies on OpenGL with non ES features, and also uses GLU)

writing the android specific stuff, such as a download of data on an SD card once the game is installed